The present invention relates to a method of coupling two component parts of a power tool.
Power tools which comprise a plurality of component parts are known, for example, from EP-A-899,063. In this disclosure there is shown a method of coupling a common body to any one of a plurality of heads, each of which heads is able to perform a different function.
A shortcoming with the coupling method disclosed in this arrangement is that very little accurate registration between the body and each head is necessary in order to effect a coupling. This means that some slight mis-alignment between the body and the head could be possible which in turn leads to a reduction in efficiency of the composite tool.
It is therefore an object of the present invention to at least alleviate the abovementioned shortcomings by providing a method of coupling two component parts of a power tool; the first component part having a mounting spigot with at least one channel formed therein and a generally cylindrical projection formed on the mounting spigot, the generally cylindrical projection including a side wall having a chamfered edge and wherein the side wall includes at least one channel parallel to the axis of the generally cylindrical member; the second component part having a spigot-receiving portion including at least one rib co-operable with the at least one channel formed in the mounting spigot, and a generally cylindrical housing member co-operable with the generally cylindrical projection of the first component part, the spigot receiving portion including at least one further rib co-operable with the at least one channel in the side wall of the first component part, the second component part further including a detent, the method comprising the steps of: aligning the at least one channel in the mounting spigot with the at least one co-operable rib on the spigot receiving portion; coupling the housing member with the cylindrical projection; engaging the further at least one rib of the spigot-receiving portion with the at least one channel of the side wall; and urging the chamfered edge past the detent. By provision of this multi-stage coupling process, accurate registration between the two component parts can be achieved and hence an efficiently-operating power tool can be formed.
Preferably, uncoupling of the two component parts is not possible until the detent has been moved clear of the chamfered edge.
Also, the at least one channel formed in the mounting spigot may comprise a plurality of channels.
Preferably the at least one channel formed in the mounting spigot comprises a plurality of channels. Preferably the at least one channel formed in the side wall comprises a plurality of channels. Advantageously the at least one rib of the spigot-receiving portion comprises a plurality of ribs. Advantageously the at least one further rib of the spigot-receiving portion comprises a plurality of further ribs.
In a preferred embodiment the detent comprises a resiliently biased spring.
Also the coupling of the two components may be only possible when the channels are aligned with their respective ribs.